Imagine a hospital room, door handle or kitchen surface that is free from bacteria - and not one drop of disinfectant or boiling water has been needed to zap the germs.

This could eventually be a reality thanks to a startling discovery made by scientists in Australia.

In a study, published in the journal Nature Communications, the researchers described how a dragonfly led them to a nano-tech surface that physically slays bacteria.

The surface of black silicon is covered in a forest of tiny spikes (pictured) which rip open the cell wall of any bacteria than land on it - this makes it fiercely antibacterial

They say black silicon, a substance discovered accidentally in the 1990s and now viewed as a promising semiconductor material for solar panels, can kill bacteria.

Its surface is a forest of spikes just 500 nanometres - 500 billionths of a metre - high that rip open the cell walls of any bacteria that come into contact with them, the scientists found.

It is the first time that any water-repellent surface has been found to have this quality.

Last year, the team, led by Elena Ivanova at Swinburne University of Technology in Melbourne, were stunned to find the wings of cicada insects were potent killers of Pseudomonas aeruginsoa—an opportunist germ that also infects humans and is becoming resistant to antibiotics.